Week 5: Assemblies

Overview

We will learn how to share our files with each other. We will learn the proper way to set up assemblies and how to join them together. And we will start to investigate our first project.

Homework

Let’s look at everyone’s McMaster-piece component pieces first.

Our double threaded parts will be held together with 1/4-20 threaded rods: 1/2″ lone (part# 95412A538 ) and 1″ (part# 95412A542). We will assemble in a shared folder.

Share Files

You create a folder and invite people to access it.

You should then be able to add files to the folder. We will add our double threaded parts here.

We may have to share our files as public links, download them, then upload them to the proper folder. We will see in class.

Assemblies

To create a Bottom-Up Assembly, a part-centric modeling method where parts are designed in relative isolation from the overall assembly, start a new file and save with “assembly” or something similar in the title. Use existing parts, right click on them and select “Insert into Current Design”, to pull them into your assembly.

Example ofBottom-Up Assembling and good use of the alignment tool.

To create a Top-Down Assembly, an assembly-centric modeling method where individual parts are defined within the context of the overall assembly, start and save a new file with “assembly” in the title. You create new components, go to Assemble and Create new component, and keep adding new components to your assembly. –via

Whether you choose Bottom-Up or Top-Down, the rest of the steps should be the same. Start with the part you will be attaching most of the parts, right click on it and “Ground” it. The part will now not move and everything can be attached to it.

Create Joints between parts. At first we’ll use rigid joints. Under Assemble, click Joint. Click a point on one part and a point on another.

We can edit the joint type. Change the Motion from “Rigid” to “Revolute”. Now we can animate it.

You can “Edit Joint Limits” to create even more specific motion.

Example of creating a Revolute Joint

Motion Link defines rotational and translational relationships between joint degrees of freedom. Watch the video below and it will clear everything up.

Example of creating a Cylindrical Joint

Linkages

We will be creating 4 bar linkages for our first project. We will design the path we want it to take.

Why a 4 Bar Linkage? Conceptually, the 4 bar linkage is straight forward, four links connected in a loop by four joints. But this mechanism can create very interesting and useful motions.

https://www.instagram.com/p/CK0lzwBDxl2/

4 Bar Linkages may be easy enough to understand, but I find them incredibly difficult to design and build. Lucky for us Mechanical Expression has created a very useful simulator.

Desired path of 4 bar linkage using Mechanical Expression

I’ve used linkages in a few projects of mine. I’ll show you the process. Block Pusher.

https://www.instagram.com/p/CGsnA6jlQ5W/

Assignment

Insert your threaded part to the shared assembly. Make sure you join it to another part.

Create an assembly. Have multiple parts and animate them. Similar to the in class exercise. Post images and video grab on your blog.

Run the Mechanical Expression simulator to get the path you desire. Develop a project idea for this motion. Record your values for AB, BC, CD, AD, BF, and FE. Take a screen shot of the desired path and post thi and your project idea to your blog.

Related Viewing

Computational Design for Mechanical Characters

David Rector’s YouTube Channel

Marvelous Mechanism: The Ubiquitous 4 Bar Linkage

Amazing Mechanical Linkages and the Software to Design Them

Linkage Mechanism Designer and Simulator

How to Share a Fusion 360 Design

Align vs Joint